Question 1

Critically evaluate the role of non-invasive ventilation (NIV) in critically ill patients.

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College Answer


NIV provides ventilatory support for patients with respiratory failure via a sealed face-mask, nasal mask, mouthpiece, full face visor or helmet without the need for intubation. Ventilatory support may be with CPAP or bi-level modes and delivered by a range of ventilators from specifically designed devices to full-service ICU ventilators.

NIV decreases resource utilisation compared with invasive ventilation and avoids the associated complications.

Patient selection and a well-designed clinical protocol are important to avoid delaying intubation in patients who are not suitable for and/or failing NIV.


  • APO – alveolar recruitment, decreased afterload, decreased work of breathing
  • COPD – decrease work of breathing and unload respiratory muscles
  • Immunosuppressed
  • Planned strategy post extubation in selected patients
  • OSA / Obesity hypoventilation syndrome
  • Asthma
  • Patients with not for intubation/ treatment limitation orders who may qualify for HDU admission or admission to respiratory care units
  • Post-operative patients – in selected patients
  • Rib fractures
  • Cystic fibrosis as bridge to transplantation

Evidence for its use:

  • APO – studies show decreased intubation rate and faster time to resolution of respiratory failure and reduction in mortality and hospital length of stay
  • COPD – RCTs and Cochrane review (14 RCTs) showed significant improvement in intubation rates, complications, length of hospital stay and mortality rates for NIV compared with invasive ventilation
  • Immunocompromised - – 2 studies, one looking at solid organ transplant recipients and one looking at patients with haematological malignancy showed benefit with NIV, i.e. fewer intubations, complications and reduced ICU and hospital mortality
  • Asthma – probably beneficial but limited evidence
  • Rib fractures – fewer episodes of pneumonia but no mortality benefit and limited evidence

Evidence against its use:

  • Use as rescue strategy for failed extubation – delays time to re-intubation. May be of benefit as part of weaning strategy and planned intervention post extubation especially in COPD patients
  • ARDS – not recommended as first line therapy

Predictors of success

  • Younger age
  • Unimpaired conscious state
  • Moderate rather than severe hypercarbia
  • Rapid improvement in physiological parameters


  • Coma
  • Cardiac / respiratory arrest
  • Cardiac instability – shock, ventricular dysrhythmias, severe acute myocardial ischaemia GI bleeding
  • Intractable vomiting
  • Inability to protect airway – poor cough, excessive secretions, decreased conscious state Upper airway obstruction
  • Following upper GI surgery (some debate about this)


  • Facial and nasal trauma and pressure sores
  • Gastric distension
  • Dry mucous membranes
  • Aspiration of gastric contents


  • Invasive ventilation
  • HFNP – may provide CPAP 5mm Hg

Summary statement / My Practice

Such as:

  • Role of NIV in critically ill includes APO and respiratory failure in COPD and immunosuppressed patients. In my practice I use NIV as a planned strategy post-extubation in selected patients and as ventilatory support for patients with respiratory failure and treatment directives limiting care. I do allow its use to delay or withhold intubation in those who need this.

Additional Examiners’ Comments:

NIV is a fundamental part of intensive care practice and the overall level of understanding was poor. Few candidates were able to demonstrate detailed knowledge of this core therapy.

Candidates were not expected to include as much detail to score good marks. Essential points included indications, some mention of evidence for and against, contra-indications and complications. Candidates were given credit if they included valid points not in the answer template.


There is no way anybody could write all that in ten minutes unless they had a prefabricated answer all loaded and ready to go in their head.  

Rationale for NIV

  • Positive pressure ventilation in general has benefits which are common to both NIV and IPPV.
  • NIV has advantages when compared to IPPV:
    • Decreased cost
    • Better tolerated (no need for sedation)
    • More convenient
    • Better availability outside of the ICU setting (eg. domiciliary)
    • Ability to interrupt therapy for breaks allows easier weaning from mechanical support

Strong indications for NIV

  • Cardiogenic pulmonary oedema: improves survival, decreases rate of intubation (Cochrane review)
  • COPD: halves mortality when compared to invasive ventilation (Cochrane review)
  • Obesity hypoventilation sydrome: mainstay of chronic maintenance and rescue for acute respiratory failure (Carrillo et al, 2012)
  • Rib fractures and chest trauma: reduced mortality, intubation rate and infections (Chiumillo et al, 2013)

Weak indications for NIV

  • Asthma:  no mortality benefit, but prevents intubation, decreases ICU stay and imrpoves delivery of nebulised drugs (Lim et al, 2012)
  • Weaning COPD patients from invasive ventilation: improves mortality, reduces VAP risk (Cochrane review)
  • Elective extubation of patients without respiratory failure: Cooperative hypercapneic high-risk patients may benefit (Ferrer et al, 2006) but not all-comers (Su et al, 2012) and it may actually be dangerous in unselected patients (Esteban et al, 2004) as waiting for NIV to work in a patient who clearly requires re-intubation is a pointless time-wasting exercise with an associated increase in mortality.
  • Ventilation for cystic fibrosis patients awaiting lung transplant: based on small-scale observational studies (Bright-Thomas et al, 2013)
  • Community-acquired pneumonia: useful in patients with pre-existing cardiac or respiratory disease (Carrillo et al, 2012)
  • Post-operative respiratory failure- "prophylactic NIV" - little data in support of this (Jaber et al, 2012)
  • Lung infection in the neutropenic patient: improves survival when compared to intubation (one small trial
  • Limitations of therapy: if the patient requires intubation but is "not for " intubation; NIV provides comfort (Azoulay et al, 2010)

Disadvantages when compared to invasive ventilation

  • More difficult to manage with an uncooperative patient
  • Cannot be used in physically restrained patients (what if they vomit? They cannot remove the mask)
  • Prevents the effective clearance of secretions and impairs physiotherapy access for suctioning
  • Cannot be performed on patients with a decreased level of consciousnes
  • Mask-face interface is difficult to manage: "one size fits all" masks do not in fact fit all; patients with unusual anatomy or little facial soft tissue (eg. in cachexia) will have more difficulty
  • Mask leak is uncomfortable and decreaseas the effectiveness of the therapy
  • Work of breathing may be increased

Contraindications for NIV

  • Decreased level of consciousness
  • Respiratory arrest
  • Vomiting
  • Hemodynamic instability
  • Poor clearance of secretions, eg. absent cough and gag
  • large sputum load and/or pneumonia
  • surgical or traumatic damage to the airways or oesophagus

Complications of NIV

  • Mask intolerance, agitation and claustrophobia
  • Increased need for sedation
  • Delay of intubation
  • Aspiration
  • Poor clearance of secretions
  • Hypotension of hypovolemic patients
  • Facial pressure areas
  • Raised intracranial pressure
  • Aerophagy
  • Damage to facial, nasal and oesophageal surgical sites or traumatic injuries, leading to surgical emphysema, pneumothorax and pneumomediastinum


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Lightowler, Josephine V., et al. "Non-invasive positive pressure ventilation to treat respiratory failure resulting from exacerbations of chronic obstructive pulmonary disease: Cochrane systematic review and meta-analysis." BMJ: British Medical Journal 326.7382 (2003): 185.

Ram, F. S., et al. "Non-invasive positive pressure ventilation for treatment of respiratory failure due to exacerbations of chronic obstructive pulmonary disease." Cochrane Database Syst Rev 3.3 (2004).

Gay, Peter C. "Complications of noninvasive ventilation in acute care."Respiratory care 54.2 (2009): 246-258.

Carrillo, Andres, et al. "Noninvasive ventilation in acute hypercapnic respiratory failure caused by obesity hypoventilation syndrome and chronic obstructive pulmonary disease." American journal of respiratory and critical care medicine 186.12 (2012): 1279-1285.

Chiumello, D., et al. "Noninvasive ventilation in chest trauma: systematic review and meta-analysis." Intensive care medicine 39.7 (2013): 1171-1180.

Lim, Wei Jie, et al. "Non-invasive positive pressure ventilation for treatment of respiratory failure due to severe acute exacerbations of asthma." The Cochrane Library Published Online: 12 DEC 2012

Alonso, Ana Souto, Pedro Jorge Marcos Rodriguez, and Carlos J. Egea Santaolalla. "Long-Term Noninvasive Ventilation Among Chronic Respiratory Failure Diseases (Cystic Fibrosis and Other Diseases) Awaiting Lung Transplantation: Key Determinants and Practical Implications." Noninvasive Mechanical Ventilation. Springer International Publishing, 2016. 771-779.

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Jaber, Samir, Gerald Chanques, and Boris Jung. "Postoperative non-invasive Ventilation." Intensive Care Medicine. Springer New York, 2008. 310-319.

Azoulay, Élie, et al. "Palliative noninvasive ventilation in patients with acute respiratory failure." Intensive care medicine 37.8 (2011): 1250-1257.

Azoulay, Élie, et al. "Noninvasive mechanical ventilation in patients having declined tracheal intubation." Intensive care medicine 39.2 (2013): 292-301.

Ferrer, Miquel, et al. "Early noninvasive ventilation averts extubation failure in patients at risk: a randomized trial." American journal of respiratory and critical care medicine 173.2 (2006): 164-170.

Su, Chien-Ling, et al. "Preventive use of noninvasive ventilation after extubation: a prospective, multicenter randomized controlled trial." Respiratory care 57.2 (2012): 204-210.

Esteban, Andrés, et al. "Noninvasive positive-pressure ventilation for respiratory failure after extubation." New England Journal of Medicine 350.24 (2004): 2452-2460.

Bright-Thomas, Rowland J., and Susan C. Johnson. "What is the role of noninvasive ventilation in cystic fibrosis?." Current opinion in pulmonary medicine 20.6 (2014): 618-622.